Valley of the Titans Missing Seal

Bug Report ID: #4032652963

https://imgur.com/a/Rj128OR

It looks like this instance of the zone "Valley of the Titans" in Act 2 only generated with 2 of the 3 seals needed for the quest. I've explored nearly the entire map and there are the two checkpoints for the two I've found, the medallion area by the waypoint, and the clasped entrance.